German police arrested a man on Friday who is suspected of planting explosives targeting the bus of soccer team Borussia Dortmund last week, the office of the German federal chief prosecutor said.

The 28-year old man, a dual German and Russian national identified as Sergei V., had bought options on Borussia Dortmund's stock before the attack, hoping to make a profit, it said in a statement.
The players' bus was heading to their stadium for a Champions League match against AS Monaco on April 11 when three explosions occurred, wounding Spanish defender Marc Bartra and delaying the match by a day.
The suspect is accused of attempted murder, inflicting serious bodily harm and causing an explosion, the prosecutor's office said.
It said he had bought 15,000 put options, or contracts giving him the right to sell Borussia Dortmund's shares at a pre-determined price, on the day of the attack, using a consumer loan he had signed the previous week.
"If the shares of Borussia Dortmund had fallen massively, the profit would have been several times the initial investment," the prosecutor's office said.
The serious injury or death of any of the soccer players could have resulted in such a slump, it said.
In December, a Tunisian man killed 12 people when he ploughed a truck through a Berlin Christmas market.
Security is an issue in campaigning for Germany's federal election on September 24, a tight battle in which Chancellor Angela Merkel is seeking a fourth term.
Last year, Merkel lost support to the anti-immigration Alternative for Germany (AfD) party after opening the country's doors to more than a million migrants. The AfD has since seen its ratings fall while Merkel has regained some ground.